Expandable medical implants are positioned and placed in the body during the completion of numerous contemporary medical procedures. These implants may include stents, vena-cava filters, and aneurism coils and may be used for innumerable purposes including reinforcing damaged vessels, replacing ruptured vessels, and delivering therapeutic to a target site in the body. This therapeutic may be delivered via coatings placed in, on, and around the implants as well as through various other means and methods.
When, for example, the therapeutic is delivered by a coated expandable implant, the coating can be damaged both during assembly and, afterwards, during the actual medical procedure. When an implant having a therapeutic coating is being assembled, the coating is routinely at risk of damage. For instance, during the crimping of balloon expandable stents onto their carrier balloon catheters, large compressive forces are exerted onto the coating of the stent in order to secure the stent to the balloon.
Even after a stent has been crimped onto a catheter, the coating is also at risk of being damaged during the delivery of the stent. For example, an expandable stent is often delivered by a balloon catheter that is expanded after the catheter reaches the target site. At a target site, when the stent is being deployed, as the balloon is expanded and both shear and torsional forces are placed on the coating by the expanding balloon. These forces can be counterproductive if too large because they can tear the coating away from and off of the stent. This tearing away can cause the therapeutic to be haphazardly adhered to the stent and, thus, reduce its effectiveness.